[ozzy 79]

Hi guys,

So... my 1979 5 speed with 82 engine is finally in running order... clutch has been overhauled... exhaust manifold machined... sounding good and looking nice.

In my 81 auto I could do 0 - 60mph in about 12 seconds (3 seconds slower than the figure I see in books and on the Net for a 280zx). Yesterday I tried the 79 out. According to the official time keeper (my girlfriend) - 14 seconds.

The car hesitates a bit in 1st. I'm hesitant to drop the clutch after just paying $800 Aust to get it fixed. Oh, and had a bit of slipping when I changed to 2nd. Very probably a driver issue... But anyways - my gameplan was to stay in each gear until hitting 5500rpm. I reached 100kph (60mph) soon after 3rd gear.

Should I be changing differently? Should I be skipping any gears? Should I get out of 1st quicker? Does it all just depend on the car and require a lot more test runs trying different things until I get a faster time?

Without mods on a 22 year old car or extensive rebuilding is the 9 second mark not achievable?

 

[zphreek]

maybe you just need to get a better timekeeper????

 

[Tony D]

6000 rpm.

You may want to try and pull to 6000 in each of the first two gears. Maybe even 6500. It really depends on what the rpm's drop to on the upshift. You want the engine above 3500 rpm, and ideally at 4000 rpm or above to keep in the fat part of the torque band for maximum acelleration.
Second, gear the car for 100kph to happen at the shift point of second gear. That is absolutely the quickest way to get the lowest 0-100 times (0-60 here in the US...)
My 2-Liter Fairlady Z would pull a 9 or 10 second 0-100 easily, with 3.70 gears, and the engine at something like 6500 as the needle crossed the "100" point.
Then again, you COULD get a G-Tech, as it will start the clock when you actually start rolling, and stop the clock at a calculated 100KPH.

But you should be able to do WELL better than 12 sec...

 

[New2Zs]

Re: 6000 rpm.

I get 8 sec in my 83zx N/A 0-60 and thats with me hitting the start/stop on the factory stop watch built into the clock....mines an automatic......no modifications....just got it...

 

[zmefly]

Re: 6000 rpm.

i can hit sixty or 100 kph in my 240 while still in second gear. what gives with the l28 cant it take the high revs?? seems like it should. james

 

[Tony D]

chances are...

you are not getting to 100 as fast as you could in your 240, either. The fastest way is to do it with the lowest numerical gearset that will allow you to hit 100 at the top of second near redline. The 240 will pull to 7000 if setup correctly, and needs to rev that high to get it'sw max power. A 240 needs like a 3.90 or 4.11 to hit 100 at the top of second at redline. The 3.36 is to high of a gear and it bogs off the line, loosing speed and time...
The L28 likes shifts around 6500, unlike the L24/L26, which like a higher shift point. He IS babying the car, true!

 

[ozzy 79]

Re: chances are...

http://www.zcar.com/forums/read.php?f=1&i=220942&t=220855

I read this post a while ago, and the followup by Madeline, and figured if Madeline agrees, it must be true. So that's why I didn't bother going over 5500rpm.

I don't know what the car's gearset is. Don't know if it's an 82 tranny or 79, if that makes any diffrence either.

 

[Tony D]

Right, 5500...

That's all applicable assuming your gear ratio drops are identical and your car is identical, and your road is identical.....
See where this is going. There are differences in vehicles. What is important, is that you find out where your shift point puts you on the upshift. If it is below peak torque of the motor, you need to overrev the engine a bit to not go below the peak torque point (or the point where the flat part of the torque band starts, at least!).
You loose less time over-revving and engine in the upper end of the rpm range, than you do lugging it below peak torque.
You only need about 25 HP to go 100kph, so you've got that covered in your car. ****, in aEVERY car. What accellerates you is TORQUE, and you need to shift on torque peaks for acceleration, not HP.

 

[Jeremy260Z]

Re: Right, 5500...

14 seems very slow. I'd say you should be able to get a stock car to do maybe a little over 10, the car being a 2+2.

Takeoff is very important, and after spending big bucks on a clutch i dont spose you want to give it much.
Rev to about 2500rpm or so for take off.

I have an 280zx L28 EFI motor and a 260Z 5 speed in my 260Z and I can pull about 110kph out of second gear, I'd estimate it was around 5500rpm [i was looking at the road, not the tach ].
You really wont have much extra power over 5500 though, but like Tony pointed out, you need the revs up when you shift. 3.5-5k rpm is probably the peak acceleration range.

Also, if i remember right, you are new to manuals. How are you shifting? You need to shift pretty quickly so you dont lose too many RPM in the shift.

I'd try a few more times and just start playing around with the takeoff, the shift and the shift rpm.

Good luck!

Jeremy

 

[Son of Magni]

Re: Right, 5500...

Yes Jer, it's very importent to get your shifting down to the fastest possible. 1/4 second to get from 1 to 2 is a lot, from disengage to engage. But it takes a long to learn to do it. A short throw shifter helps too. Also if your linkage bushings are worn out, it'll slow you down a lot, especially from 2 to 3.

But (as has been said above, sorry if I repeat something) each time you shift, make sure the rpm you shift into is high enough to give you the torque you need (3500-4000 minimum) scary as it seems...
SoM

 

[steve260z]

Am I way out of line by saying that my 74 260 pulls 100 Km/h in second fairly easily (6200 rpm)? I have never actually timed a 0-60 mph in my car but I swear that it is a **** sight faster than 14 seconds, or 12 seconds for that matter. Another thing, maybe. I found my car was slower with the 5 speed that was in it when I bought it than it is with the 4 speed now. Maybe I'm just losing my mind...
It shouldn't be too horribly difficult to hit a 9 second 0-60 time, though it may take some work.

 

[zbartsky]

Um was this guys grlfriend in the car at the time? That will slow you down a lot!!